Do antithyroid antibodies affect hearing outcomes in patients with pediatric euthyroid Hashimoto's thyroiditis?

Objectives: Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease in children. HT is a multifaceted disease with a variable clinicopathological presentation, including hearing impairment. It is known that hearing function is negatively affected in patients with thyroid disorders. The literature includes a very limited number of studies on hearing function in euthyroid pediatric patients with HT. The aim of this study was to determine the relationship between cochlear function and HT, independent of thyroid function.

Materials and methods: The study included 48 children and adolescents (42 females and 6 males) aged 9-18 years that were diagnosed as HT, and 30 gender- and age-matched healthy controls. Hearing was assessed via otoscopy, tympanometry, pure-tone audiometry, and measurement of distortion product otoacoustic emissions.

Results: There weren't any significant differences in pure tone thresholds between the 2 groups based on pure-tone audiometry, except in the right ear at 6kHz and 8kHz. Distortion product otoacoustic emissions signal to noise ratios were significantly lower in the HT group than in the control group at 4 different frequencies (6kHz [left ear], 8kHz [left ear], 1.5kHz [right ear], and 6kHz [right ear]) (P<0.05). The signal to noise ratios at all frequencies were <6dB in 3% of left ears and 2.5% of right ears in the control group, versus 12.5% of left ears and 9.6% of right ears in the HT group. Distortion product amplitudes were significantly lower in the HT group than in the control group for both left and right ears at 1kHz, 1.5kHz, 3kHz, and 8kHz, and at 2kHz for left ears only (P<0.05).

Conclusions: The present findings show that cochlear function was lower in the HT group than in the control group. Accordingly, we think that hearing in patients with HT should be monitored periodically, even if their hearing thresholds are within normal limits. Thyroid autoimmunity appears to play an important role in a decrease in cochlear activity in pediatric HT patients.